JP5250692B2 - Permanent magnet rotating electric machine - Google Patents

Description

  The present invention relates to a permanent magnet type rotating electrical machine, and more particularly to a permanent magnet type rotating electrical machine suitable for a generator or an electric motor whose rotational direction is always limited to one direction.

  In recent years, the adoption of permanent magnet type rotating electrical machines has increased dramatically in each field of rotating electrical machines. In order to improve economy by increasing the single machine capacity of the permanent magnet type rotating electric machine, demand for a small and large capacity permanent magnet type rotating electric machine is increasing. However, if the permanent magnet generator is reduced in size and increased in capacity, the amount of heat generation increases. Therefore, as shown in FIG. 1 of Patent Document 1, the permanent magnet rotation in which a cooling air passage is formed between the magnetic poles. Electrics have been proposed.

  By forming a cooling air passage between the magnetic poles, the amount of heat generated can be suppressed, and the permanent magnet type rotating electrical machine can be reduced in size accordingly. However, by forming a cooling ventilation path between the magnetic poles, the magnetic flux concentrates on the magnetic poles, which increases torque pulsation and increases vibration and noise.

  In order to reduce the concentration of the magnetic flux on the magnetic pole, as shown in FIGS. 14 and 15 of Patent Document 1, the gap between the outer peripheral surface of the magnetic pole and the stator is set at both ends in the circumferential direction compared to the central portion of the magnetic pole. By enlarging on the part side, the concentration of magnetic flux is alleviated and torque pulsation is reduced.

JP 2008-131814 A

  In the permanent magnet type rotating electric machine according to Patent Document 1, it is possible to reduce torque pulsation.

  On the other hand, in a permanent magnet type rotating electrical machine that always rotates in only one direction, the concentration of magnetic flux on the magnetic pole is limited to one side in the rotational direction as compared with a rotating electrical machine that rotates in both directions.

  However, in a permanent magnet type rotating electrical machine that always rotates in only one direction, there is a technique for reducing the magnetic flux concentrated on one side in the rotational direction of the magnetic pole peripheral surface having the permanent magnet (with the permanent magnet embedded). do not do. The reason for this is that in a permanent magnet type rotating electrical machine, a permanent magnet is embedded in the vicinity of the peripheral surface of the magnetic pole. Therefore, if an attempt is made to widen the gap with the stator by changing the shape of the peripheral surface of the magnetic pole, This is because the rotor core around the buried position becomes thin, and it may be difficult to ensure the mechanical strength for holding the permanent magnet against the centrifugal force and electromagnetic force during operation.

  An object of the present invention is to provide a permanent magnet type rotating electrical machine that can reduce magnetic flux concentrated on one side in the rotation direction of a magnetic pole peripheral surface that causes torque pulsation and can ensure mechanical strength. is there.

  In order to achieve the above object, in the present invention, the outer periphery of each magnetic pole is formed by an arc having the same curvature, and the magnetic pole central axis of each magnetic pole is displaced with respect to the rotation center of the rotor to The gap with the outer periphery of the magnetic pole is made wider on one side in the rotational direction than on the other side.

  In this way, the outer periphery of each magnetic pole is formed into an arc having the same curvature, and the magnetic pole central axis of each magnetic pole is displaced with respect to the rotation center of the rotor, thereby forming the rotor core around the permanent magnet embedded position. Since there is no need to reduce the thickness, the mechanical strength for holding the permanent magnet against centrifugal force and electromagnetic force during operation can be secured, and the gap between the stator and the outer periphery of each magnetic pole can be turned from one side to the other. Since it is wider than that, the concentration of magnetic flux can be relaxed.

  As described above, according to the present invention, the permanent magnet type rotating electrical machine that can reduce the magnetic flux concentrated on one side in the rotation direction of the magnetic pole peripheral surface that causes torque pulsation and can ensure the mechanical strength. Can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic longitudinal cross-sectional view of the permanent-magnet-type generator which shows 1st Embodiment of the permanent-magnet-type rotary electric machine by this invention. FIG. 2 is a longitudinal enlarged view of a rotor taken along line AA in FIG. 1. The enlarged view of the magnetic pole of the rotor shown in FIG. The torque waveform figure of the permanent magnet type generator by 1st Embodiment. The partial front view of the rotor which shows the modification of 1st Embodiment. The torque waveform figure of the permanent magnet type generator by the modification of 1st Embodiment. FIG. 2 is a view corresponding to FIG. 2 showing a second embodiment of the permanent magnet type rotating electric machine according to the present invention. The enlarged view of the magnetic pole of the rotor shown in FIG. FIG. 2 is a view corresponding to FIG. 2 showing a third embodiment of the permanent magnet type rotating electric machine according to the present invention. The front view of the rotor which shows the 1st modification of 3rd Embodiment. The front view of the rotor which shows the 2nd modification of 3rd Embodiment. FIG. 2 shows a fourth embodiment of the permanent magnet type rotating electric machine according to the present invention. FIG. 2 shows a fifth embodiment of the permanent magnet type rotating electric machine according to the present invention. FIG. 1 is a view corresponding to FIG. 1 showing a sixth embodiment of a permanent magnet type rotating electric machine according to the present invention. Schematic which shows the wind power generation system to which the permanent magnet generator by this invention is applied.

BEST MODE FOR CARRYING OUT THE INVENTION

  A first embodiment of a permanent magnet type rotating electrical machine according to the present invention will be described below based on the permanent magnet type generator shown in FIGS.

  The permanent magnet generator 1 includes a rotating shaft 2 that is connected to a prime mover and is rotatably supported, a rotor 3 that is fixed to the rotating shaft 2, and a stator 4 that is disposed on the outer periphery of the rotating shaft 2 via a gap. And.

  The rotor 3 includes a rotor core 5 formed by laminating electromagnetic steel plates in the axial direction, a permanent magnet 6 embedded on the outer peripheral side of the rotor core 5, and an axial extension to the rotor core 5. And cooling ventilation grooves 7 formed at even intervals with intervals in the circumferential direction. The permanent magnet 6 is embedded on the outer peripheral side of the rotor core 5 between the cooling ventilation grooves 7 adjacent in the circumferential direction to form an even number of magnetic poles 8.

  On the other hand, the stator 4 includes a stator core 9 that is installed via the rotor core 5 and a gap and is constructed by laminating electromagnetic steel plates in the axial direction, and an axial direction formed on the inner diameter side of the stator core 9. And a stator winding 10 mounted in a winding groove (not shown).

  The magnetic pole 8 has a curvature (radius) centered on the rotation center 11 of the rotor 3 and a magnetic pole center of a magnetic pole 8A having an outer periphery 8s having the same gap with the stator 4 as shown by a broken line in FIG. The shaft 12A is displaced in a tilted direction RA in the direction opposite to the rotation direction R around the inner diameter side of the rotor core 5, in other words, the magnetic pole center shaft 12A is displaced with respect to the rotation center 11 of the rotor 3. The magnetic pole 8 is formed by moving the magnetic pole central shaft 12 to the position.

  By forming the magnetic pole 8 in this manner, the outer periphery 8S of the outer periphery 8S becomes wider on the opposite side to the rotation direction R and gradually decreases as it goes to the rotation direction R side.

  Therefore, the concentration of the magnetic flux concentrated on the opposite side to the rotation direction R of each magnetic pole 8 can be relaxed by the widened gap, and as a result, the torque pulsation due to the magnetic flux concentration can be reduced.

  Incidentally, when the torque pulsation between the shape of the magnetic pole 8A shown in the broken line in FIG. 3 (conventional example) and the shape of the magnetic pole 8 formed by the displacement shown in the practice of FIG. As shown in the torque waveform, it was confirmed that the torque pulsation according to the present embodiment is reduced by about 30% compared to the conventional example.

  Furthermore, even if the magnetic pole 8 is configured by displacing the magnetic pole central axis 12, the thickness of the rotor core 5 around the embedded position of the permanent magnet 6 of the rotor 3 is not changed, and thus the permanent magnet 6 is held. The strength of the rotor core 5 is not reduced, and the permanent magnet 6 can be stably held.

  In addition, since a cooling ventilation groove 7 is formed between the adjacent magnetic poles 8, a cooling medium (air circulating inside the machine or outside air introduced from outside the machine) is inserted into the cooling ventilation groove 7 during operation. Etc.) can be distributed, so that the amount of heat generated by the permanent magnet generator 1 can be suppressed, and the permanent magnet generator 1 can be reduced in size accordingly.

  By the way, in the present embodiment, the magnetic pole central axis 12 is inclined and displaced to change the gap between the outer periphery 8S of the magnetic pole 8 and the stator 4, but as in the modification shown in FIG. Alternatively, the gap may be changed by shifting the radius center 13 of the outer periphery 8S of the magnetic pole 8 from the magnetic pole central axis 12 of the rotor 3.

  By shifting the radius center 13 of the outer periphery 8S of the magnetic pole 8 of the rotor 3 in this way, the gap with the stator 4 on the counter-rotation direction side can be further enlarged, and the concentration of magnetic flux can be efficiently reduced. Can do. As a result, as shown in FIG. 6, the torque pulsation could be reduced by about 60% compared to the conventional example.

  Next, a second embodiment according to the present invention will be described with reference to FIGS. The same reference numerals as those in FIGS. 1 to 3 and FIG.

  In the present embodiment, a configuration different from the first embodiment shown in FIG. 1 is a method of displacing the magnetic pole central axis 12B of the magnetic pole 8. That is, in the present embodiment, as shown by a broken line in FIG. 8, in the magnetic pole 8A having the outer periphery 8s with the rotation center 11 as the radius center, the magnetic pole center axis 12 passing through the rotation center 11 is directed to the rotation direction R side. The magnetic pole 8 having the same shape is formed at the position that becomes the magnetic pole central axis 12B by being translated and displaced.

  By configuring in this way, it is possible to achieve the same effect as that of the first embodiment.

  Furthermore, also in the present embodiment, as shown in the modification of the first embodiment (FIG. 5), the torque pulsation can be further reduced by shifting the radius center 13 of the outer periphery 8S of the magnetic pole 8. Can do.

  By the way, in the first and second embodiments, the number of the magnetic poles 8 of the rotor 3 is eight. However, other numbers of poles may be used. Even when the method (concentrated winding or distributed winding) is changed, the same effect can be obtained by applying the rotor 3 according to the above embodiment.

  FIG. 9 shows a third embodiment according to the present invention, which has the same configuration as that of the first and second embodiments, except that the embedded position of the permanent magnet 6 in the rotor core 5 is different.

  That is, in the first and second embodiments, the permanent magnet 6 uses two flat magnets 6 having a rectangular cross section and is embedded in one magnetic pole 8 in a V shape. However, in the present embodiment, two flat permanent magnets 6 are embedded in parallel so that the plate surfaces are the same.

  Also in this embodiment, the same effect as the above-described embodiment can be obtained.

  Further, FIG. 10 shows a first modification of the third embodiment, in which two flat permanent magnets 6 are used and one magnetic pole 8 is embedded in a “C” shape.

  FIG. 11 shows a second modification example of the third embodiment, in which two permanent magnets 6A having a circular cross section are used, and a single magnetic pole 8 has an arc along the outer periphery 8S. It is buried like this.

As shown in the third embodiment and the two modifications based thereon, by selecting the embedding method of the permanent magnets 6 and 6A according to the formation state of the outer periphery 8S of the magnetic pole 8, the permanent magnets 6 and 6A can be selected. The thickness of the rotor core 5 in the vicinity can be ensured, and the mechanical strength can be ensured.
FIG. 12 shows a fourth embodiment according to the present invention. The permanent magnet 6 embedded in the rotor core 5 is divided into a plurality of permanent magnet pieces 6a, 6b, 6c, 6d in the width direction. It was configured.

  In this way, by configuring the permanent magnet 6 with the permanent magnet pieces 6a, 6b, 6c, and 6d, heat generation of the permanent magnet 6 due to eddy current loss can be suppressed low, and the permanent magnet generator can be reduced in size and size. It can contribute to capacity increase.

  Needless to say, the subdivision of the permanent magnet 6 is not limited to the present embodiment, but can be applied to the permanent magnets 6 and 6A shown in other embodiments and modifications.

  In each of the above explanations, the cooling grooves 7 are provided to cool the rotor 3 so that the magnetic poles 8 are formed. However, further cooling of the rotor 3 may be required. In such a case, as in the fifth embodiment according to the present invention shown in FIG. 13, for each magnetic pole 8, a hole 14 penetrating in the axial direction is provided on the inner diameter side of the embedded position of the permanent magnet 6. The cooling capacity can be improved by forming a directional cooling passage and circulating the cooling medium therethrough.

  Next, a sixth embodiment according to the present invention will be described with reference to FIG. Since the same reference numerals as those in the first embodiment indicate the same constituent members, detailed description thereof is omitted.

  The configuration different from that of the first embodiment is that the hole 14 shown in FIG. 13 is provided on the inner diameter side of the rotor core 5 to form an axial cooling passage, and electromagnetic waves are provided at a plurality of locations in the axial direction of the rotor core 5. A point in which a radial ventilation duct 15 is formed when laminating steel plates, a point in which a similar ventilation duct 16 is formed in the stator core 9, and a rotation shaft 2 positioned on both axial sides of the rotor 3. This is the point that the flow fans 17A and 17B are provided.

With this configuration, the cooling medium is pushed into the cooling ventilation groove (not shown) 7 and the hole 14 of the rotor core 5 by the axial fans 17A and 17B, and then passes through the ventilation duct 15 to have a radius. Since it flows in the direction and then returns to the axial fans 17A and 17B through the ventilation duct 16 of the stator 4, the cooling efficiency of the rotor 3 and the stator 4 can be increased, and the permanent magnet generator 1 can be reduced in size. Although not shown, heat exchange is performed in the middle of the flow path of the cooling medium circulated by the axial fans 17A and 17B, for example, on the outer peripheral side of the stator 4. If a vessel is installed, it can contribute to further improvement in cooling efficiency.

  Further, FIG. 15 shows an example in which the permanent magnet generator 1 according to each embodiment is applied to a wind power generation system.

  The permanent magnet generator 1 is rotationally connected to a windmill 18 that is a prime mover via a speed reduction means 19. The permanent magnet generator 1 and the speed reduction means 19 are installed in a windmill nacelle 20. The permanent magnet generator 1 is electrically connected to the load 21 via the power converter 22 and performs a power generation operation.

  The permanent magnet generator 1 is rotationally connected to the windmill 18 via the speed reduction means 19, but may be directly connected to the windmill 18.

  Thus, the windmill nacelle 20 whole can be reduced in size by applying the small-sized and large-capacity permanent magnet generator 1 according to the present invention to the wind power generation system.

  By the way, in the above explanation, the gap between the outer periphery of the magnetic pole and the stator at the position on the tip side in the rotational direction is set to the gap between the outer periphery of the magnetic pole and the stator at the position on the counter-rotation direction. Since it is gradually reduced along the outer peripheral arc, the concentration of the magnetic flux toward the lower side of the magnetic pole can be gently dispersed and reduced. However, when the gap between the stator and the stator is changed by linearly tilting the outer circumference of the magnetic pole, conversely, the magnetic flux tends to concentrate on the part where the gap between the stator and the stator is closest, and the effect of reducing the concentration of the magnetic flux is reduced. Cannot be demonstrated. Therefore, the gap with the stator needs to be gradually reduced along the arc on the outer periphery of the magnetic pole.

  In addition, when forming an arc around the magnetic pole, an example was shown in which an arc with a single radius center was formed. However, depending on the application and characteristics of the permanent magnet generator, the arc having an outer periphery with a plurality of radius centers May be formed.

  In addition, the permanent magnet may be divided into a plurality of parts in the axial direction in consideration of assemblability and the like.

  Although each said embodiment demonstrated the permanent-magnet-type generator applicable to a wind power generation system, it can also be connected and used for a turbine, an engine, a turbine, etc. as a motor.

  Furthermore, the permanent magnet type rotating electrical machine according to the present invention can be applied to a permanent magnet type electric motor. When the permanent magnet type rotating electrical machine is a permanent magnet type electric motor, the gap between the outer periphery of the magnetic pole and the stator at the position on the front end side in the rotational direction is the position of the outer periphery of the magnetic pole in the position on the opposite side of the rotational direction. It is important to make it wider than the gap with the stator.

Claims (11)

  A stator, and a rotor rotatably supported by a stator through a gap, and a cooling ventilation groove extending in an axial direction in the rotor iron core of the rotor is circumferentially spaced; In the permanent magnet type rotating electrical machine in which an even number of magnetic poles are formed by embedding a permanent magnet in a rotor core between adjacent cooling ventilation grooves in the circumferential direction, the outer periphery of each of the even numbered magnetic poles has the same curvature. The magnetic pole central axis of each magnetic pole is displaced with respect to the rotation center of the rotor, and the gap between the stator and each magnetic pole outer periphery is made wider on one side in the rotation direction than on the other side. Permanent magnet type rotating electrical machine characterized by   2. The permanent magnet type rotating electrical machine according to claim 1, wherein the arcs formed on the outer periphery of each of the magnetic poles are each formed into an arc having the same radius.   The arcs formed on the outer periphery of each of the magnetic poles are each formed into an arc of the same radius, and each of the magnetic poles is formed by inclining the central axis of the magnetic pole to one side in the rotation direction. 1. A permanent magnet type rotating electrical machine according to 1.   The arcs formed on the outer peripheries of the respective magnetic poles are formed into arcs having the same radius, and each magnetic pole moves in parallel with the central axis of the magnetic pole to one side in the rotation direction with respect to a central straight line passing through the rotation center of the rotor. The permanent magnet generator according to claim 1, wherein the permanent magnet generator is formed. The permanent cooling system according to any one of claims 1 to 4 , wherein an axial cooling passage is formed in an inner diameter side of the permanent magnet of the rotor iron core in parallel with the cooling ventilation groove. Magnet rotating electric machine. The permanent magnet type rotating electrical machine according to any one of claims 1 to 4 , wherein a radial ventilation duct is formed at a plurality of axial positions of the rotor core. An axial cooling passage is formed in parallel to the cooling ventilation groove on the inner diameter side of the embedded position of the permanent magnet of the rotor core, and the axial direction is provided at a plurality of locations in the axial direction of the rotor core. permanent magnet rotating electrical machine according to any one of claims 1 to 4, characterized in that the radial ventilation ducts communicating with the air passage is formed. The permanent magnet according to any one of claims 1 to 7 , wherein the rotor has two flat plate permanent magnets each having a rectangular cross section arranged at intervals in the circumferential direction for each magnetic pole. Rotary electric machine. The permanent magnet according to any one of claims 1 to 7 , wherein the rotor has permanent magnets formed in two arcs in cross section for each magnetic pole and arranged in parallel at intervals in the circumferential direction. Magnet rotating electric machine. The permanent magnet rotating electric machine according to claim 8 or 9 , wherein the flat permanent magnet is divided in an axial direction. A wind power generation system using the permanent magnet type rotating electrical machine according to any one of claims 1 to 10 as a generator.

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